The invention relates to a novel crystal form of a perinone dye of the formula (I), a process for its preparation and its use for mass coloration of plastics.
The dye of the formula (I) (=C.I. Solvent Orange 60) when prepared in the prior art, for example as in EP-A-780 444 or in B. K. Manukian Helv. Chimica Acta 1965, Vol. 48, p. 1999-2004, is in the -form whose X-ray diffraction diagram (C-K radiation) is reproduced in FIG. 1 and which is characterized by lines at the following diffraction angles 2 (°)9.911, 11.799, 12.412, 13.150, 23.682, 24.122, 24.852, 26.765, 27.476.
The dye of the formula (I) In the α-form is a widely used colorant for mass coloration of plastics and other applications. However, there are a number of disadvantages in need of improvement. For instance, the known dye in powder form has a low bulk density and is prone to dusting in handling. Moreover, production of a granular or pulverulent product by spray drying of an aqueous slurry is uneconomical because of the very low solids content of the slurry.
It is an object of the present invention to remedy these disadvantages.